Arias Dayana, Cisternas Luis A, Miranda Carol, Rivas Mariella
Departamento de Ingeniería Química y Procesos de Minerales, Universidad de Antofagasta, Antofagasta, Chile.
Laboratorio de Biotecnología Algal y Sustentabilidad (BIOAL), Departamento de Biotecnología, Facultad de Ciencias del Mar y Recursos Biológicos, Universidad de Antofagasta, Antofagasta, Chile.
Front Bioeng Biotechnol. 2019 Jan 18;6:209. doi: 10.3389/fbioe.2018.00209. eCollection 2018.
The processes of biomineralization, mediated by ureolytic bacteria, possess a wide range of technological applications, such as the formation of biocements and remediation of water and soil environments. For this reason, the bioprospecting of new ureolytic bacteria is interesting for its application to these technologies, particularly for water treatment. This study demonstrates the isolation, selection, and identification of halotolerant ureolytic bacteria from Laguna Salada (inland from Atacama Desert) and the evaluation of their ability to precipitate calcium carbonate crystals in freshwater in the presence of calcium ions, as well as the ability to induce the precipitation of crystals from different ions present in seawater. Twenty-four halotolerant ureolytic bacteria whose molecular identification gives between 99 and 100% identity with species of the genus , and were isolated. When cultivated in freshwater, urea, and calcium chloride, all species are able to biomineralize calcium carbonate in different concentrations. In seawater, the strains that biomineralize the highest concentration of calcium carbonate correspond to and sp. SEM-EDX and XRD analyses determined that both bacteria induce the formation of 9-33% halite (NaCl), 31-66% monohydrocalcite (CaCO × HO), and 24-27% struvite (MgNHPO × 6HO). Additionally, induces the formation of 7% anhydrite (CaSO). In seawater, and sp. were able to precipitate both calcium (96-97%) and magnesium (63-67%) ions over 14 days of testing. Ion removal assays with immobilized in beads indicate a direct relationship between the urea concentration and a greater removal of ions with similar rates to free cells. These results demonstrate that the biomineralization mediated by bacterial urea hydrolysis is feasible in both freshwater and seawater, and we propose its application as a new technology in improving water quality for industrial uses.
由尿素分解菌介导的生物矿化过程具有广泛的技术应用，例如生物水泥的形成以及水和土壤环境的修复。因此，新的尿素分解菌的生物勘探因其在这些技术中的应用而备受关注，特别是在水处理方面。本研究展示了从拉古纳·萨拉达（阿塔卡马沙漠内陆）分离、筛选和鉴定耐盐尿素分解菌，并评估它们在钙离子存在下在淡水中沉淀碳酸钙晶体的能力，以及从海水中存在的不同离子诱导晶体沉淀的能力。分离出了24株耐盐尿素分解菌，其分子鉴定与属和属的物种具有99%至100%的同一性。当在淡水、尿素和氯化钙中培养时，所有菌株都能够在不同浓度下生物矿化碳酸钙。在海水中，生物矿化碳酸钙浓度最高的菌株对应于和种。扫描电子显微镜-能谱仪（SEM-EDX）和X射线衍射（XRD）分析确定，这两种细菌都能诱导形成9%至33%的石盐（NaCl）、31%至66%的一水方解石（CaCO₃·H₂O）和24%至27%的鸟粪石（MgNH₄PO₄·6H₂O）。此外，还能诱导形成7%的硬石膏（CaSO₄）。在海水中，和种在14天的测试中能够沉淀钙（96%至97%）和镁（63%至67%）离子。用固定在珠子中的进行离子去除试验表明，尿素浓度与离子去除量之间存在直接关系，去除速率与游离细胞相似。这些结果表明，由细菌尿素水解介导的生物矿化在淡水和海水中都是可行的，我们建议将其作为一种改善工业用水水质的新技术加以应用。
